TITANIUM BASE ALLOY INGOTS AND BILLETS PIERCING METHOD FOR MAKING SLEEVES IN SKEW ROLLING MILLS Russian patent published in 2007 - IPC B21B21/00 

FIELD: rolled tube production, namely titanium-base alloy ingots and billets to sleeve piercing method in skew rolling mills, possibly production of conversion tubes of large- and mean diameters of titanium base alloys in tube rolling plants with pilger mills.

SUBSTANCE: method comprises steps of under-drilling ingots and billets at their shrinkage side by value 50 - 80 m; heating them in muffles and continuous furnaces till yielding temperature; guiding glass-enamel briquettes to central opening at time of cooling down 2 -3 min before starting piercing by depth 200 - 300 mm from end face; piercing sleeves in skew rolling mill; applying onto inner surface of sleeves layer of glass-enamel lubricating coating with thickness 0.3 -0.5 mm; determining diameter of glass enamel briquettes from given expression D = D_c.op.- (10 -15) where D_c.op. - diameter of central opening of ingots and billets, mm. Mass value and geometry size of glass-enamel briquettes are determined according to expression: m = h*S*g = π/4* D²*H*g where h = (0.03 -0.05)cm -thickness of layer necessary for preventing inner surface of sleeve against gas saturation; S - area of inner surface of sleeves, cm²; g - specific gravity of glass-enamel briquettes, g/cm³; D - diameter of glass-enamel briquettes, cm; H - height of glass-enamel briquettes, cm.

EFFECT: lowered or completely prevented sleeve slips and jamming in mill, decreased number of cracks and air holes, lowered depth of their penetration in body of sleeves, absence of operations for sleeve blowing after piercing and for additional lubrication of mandrels.

4 cl, 1 tbl